Governance of disaster emergency wells in three cities in Japan affected by earthquakes     

Endo  Takahiro  Iizuka  Tomoki  Koga  Hitomi  Hamada  Nahoko 《Hydrogeology Journal》2023,31(5):1147-1163

Concern has grown regarding how public and private sectors should make effective use of local groundwater to alleviate negative impacts of water-supply cutoff following an earthquake event, which can be regarded as an emergency groundwater governance problem. Existing literature on groundwater governance, however, is based on the tacit assumption of groundwater utilization under normal social conditions, and scant consideration has been given to the role of groundwater following occurrence of a natural disaster. This study conducted questionnaire surveys to reveal how groundwater was used in three cities (Kumamoto, Sapporo, and Sendai) in Japan struck by large earthquakes between 2010 and 2020. Results revealed substantial differences between these cities in terms of groundwater utilization following earthquake occurrence. The time between the restoration of the electricity supply and restoration of the waterworks, and the social capital accumulated by local governments, are indicated as possible reasons for such differences. Analysis also identified policy challenges for improved groundwater governance in an emergency: (1) establishment of a strategy for emergency water supply through combined use of groundwater and other water sources, (2) enhancement of methods for timely inspection of groundwater quality following occurrence of a disaster, (3) maintenance of records of the number of registered disaster emergency wells (DEWs), (4) creation of methods for publicizing locational information on DEWs with adequate regard for the privacy of well owners, and (5) recognition of the importance of making DEWs part of overall disaster preparedness.

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Scale factor calibration of a superconducting gravimeter at Esashi Station, Japan, using absolute gravity measurements     

Y. Tamura  T. Sato  Y. Fukuda  T. Higashi 《Journal of Geodesy》2005,78(7-8):481-488

The scale factor of a superconducting gravimeter (SG) at the Esashi Earth Tides Station, Japan, was revised by repeating co-located absolute gravity measurements with an FG5 gravimeter. Although the calibration results from the absolute gravimeter (AG) show an apparent secular change in the scale factor of the SG (0.4% for the period 1993–2002), the relative scale factors, which are determined by tidal analysis with the response method, indicate that it has changed by no more than 0.01% during the above period. If the mean scale factor over the 10 years is adopted, a value of –56.082±0.029 Gal/V (1 Gal =10^–8 m s^–2) is obtained, which is about 0.4% smaller than that used in the global geodynamics project (GGP) database. Based on this newly determined scale factor, the tidal gravity factors at Esashi have been re-estimated. The observed tidal factors, corrected for the ocean tide effects with recent models, indicate that the theoretical gravity factors for an inelastic Earth model are more consistent with the observations than are those for an elastic model.  相似文献   

A Simple Monte Carlo Method for Locating the Three-dimensional Critical Slip Surface of a Slope   总被引：2，自引：0，他引：2  

XIE Mowen Institute of Environmental Systems  Kyushu University  Hakozaki --  Higashi Ku  Fukuok  Japan College of Resource Engineering  the University of Science  Technology Beijing  Xueyuan Ro  Haidian District  Beijing  China 《《地质学报》英文版》2004,78(6):1258-1266

Based on the assumption of the plain-strain problem, various optimization or random search methods have been developed for locating the critical slip surfaces in slope-stability analysis, but none of such methods is applicable to the 3D case. In this paper, a simple Monte Carlo random simulation method is proposed to identify the 3D critical slip surface. Assuming the initial slip to be the lower part of a slip ellipsoid, the 3D critical slip surface is located by means of a minimized 3D safety factor. A column-based 3D slope stability analysis model is used to calculate this factor. In this study, some practical cases of known minimum safety factors and critical slip surfaces in 2D analysis are extended to 3D slope problems to locate the critical slip surfaces. Compared with the 2D result, the resulting 3D critical slip surface has no apparent difference in terms of only cross section, but the associated 3D safety factor is definitely higher.  相似文献   

Probing fault zone heterogeneity on the Nojima fault: Constraints from zircon fission-track analysis of borehole samples   总被引：2，自引：0，他引：2  

Takahiro Tagami  Masaki Murakami 《Tectonophysics》2007,443(3-4):139

Fission-track (FT) thermochronologic analysis was performed on zircon separates from rocks in and around the Nojima fault, which was activated during the 1995 Kobe earthquake. Samples were collected from the University Group 500 m (UG-500) borehole and nearby outcrops. FT lengths in zircons from localities > 25 m away from the fault plane as well as one 0.1 m away from the fault in the footwall are characterized by concordant mean values of  10–11 μm and unimodal distributions with negative skewness, which showed no signs of appreciable reduction in FT length. In contrast, those adjacent (< 3 m) to the fault at depths on the hanging wall side showed significantly reduced mean track lengths of  6–8 μm and distributions having a peak around 6–7 μm with rather positive skewness. The former pattern is interpreted to reflect cooling through the zircon partial annealing zone (ZPAZ), without later, partial thermal overprints. The latter indicates substantial track shortening due probably to secondary heating by a thermal event(s) that locally perturbed the geothermal structure. Modeled zircon FT length and age data of partially annealed samples from the UG-500 borehole revealed a cooling episode in the ZPAZ that started at  4 Ma within  3 m from the fault plane, whereas those from the Geological Survey of Japan 750 m borehole record cooling started at  31–38 Ma within  25 m from the fault. On the basis of one-dimensional heat conduction modeling as well as the consistency between the degree of FT annealing and the degree of deformation/alteration of borehole rocks, these cooling ages in both boreholes are interpreted as consequences of ancient thermal overprints by heat transfer or dispersion via fluids in the fault zone. Together with the zircon FT data of a pseudotachylyte layer recently analyzed, it is suggested that the present Nojima fault system was reactivated in the Middle Quaternary from an ancient fault initiated at  56 Ma at mid-crustal depths. Also shown is a temporal/spatial variation in terms of the thermal anomalies recorded in the fault rocks, implying heterogeneity of hot fluid flows in the fault zone.  相似文献   

Low‐temperature thermochronological database of bedrock in the Japanese Islands     

Shigeru Sueoka  Takahiro Tagami 《Island Arc》2019,28(4)

To provide better access to thermochronological data and understand the long‐term denudation history of the Japanese Islands, we compiled a low‐temperature thermochronological dataset of fission‐track (FT) and (U–Th–Sm)/He (He) ages for apatite and zircon in bedrocks. These thermochronometric ages are compiled from 90 literature sources and 1,096 localities, and include 418 apatite FT ages, 851 zircon FT ages, 42 apatite He ages, and 30 zircon He ages. Many FT ages have been reported previously; however, the number of He ages is limited in the Japanese Islands. The compiled data are spatially biased; for instance, more data are reported for the Chubu and Kinki districts and the Pacific coast of the Shikoku Island, whereas less data were available for the Tohoku and Chugoku districts. For better understanding arc‐scale uplift‐denudation history, further thermochronological research in the lesser‐studied regions and more He thermochronometric measurements are desired. This compilation will be updated and provided on the website of the Fission‐Track Research Group in Japan ( http://ftrgj.org/index.html ).  相似文献   

Development of a 2-km resolution ocean model covering the coastal seas around Japan for operational application     

Sakamoto  Kei  Tsujino  Hiroyuki  Nakano  Hideyuki  Urakawa  Shogo  Toyoda  Takahiro  Hirose  Nariaki  Usui  Norihisa  Yamanaka  Goro 《Ocean Dynamics》2019,69(10):1181-1202

Ocean Dynamics - In order to expand the coastal ocean monitoring and forecasting system of the Japan Meteorological Agency from the Seto Inland Sea to the entire coastal seas of Japan, a 2-km...  相似文献   

Diets of Steller sea lions off the coast of Hokkaido,Japan: An inter‐decadal and geographic comparison          下载免费PDF全文

Yoko Goto  Akihiko Wada  Noboru Hoshino  Takahiro Takashima  Masaki Mitsuhashi  Kaoru Hattori  Orio Yamamura 《Marine Ecology》2017,38(6)

Inter‐decadal and geographic variations in the diets of Steller sea lion, Eumetopias jubatus, were examined based on the contents of 408 stomachs collected from coastal areas around Hokkaido Island during the periods 1994–1998 and 2005–2012. The most important prey species in the 1990s were gadid fishes (walleye pollock [Gadus chalcogrammus], Pacific cod [Gadus microcephalus] and saffron cod [Eleginus gracilis]). The frequency of occurrence and gravimetric contribution of gadids decreased in the 2000s latter period at three study sites (Rausu, Shakotan and Rebun) and were replaced by Okhotsk Atka mackerel (Pleurogrammus azonus) and smooth lumpsucker (Aptocyclus ventricosus). However, analysis based on gravimetric composition indicated that the dietary diversity of prey showed only a slight inter‐decadal difference, reflecting the wide diversity of prey ingested during both study periods. These results indicate that Steller sea lions along the Hokkaido coast are opportunistic feeders that utilize a wide variety of prey, and appear to feed mainly upon prey that is easily obtained.  相似文献   

Simulated distribution and ecotoxicity-based assessment of chemically-dispersed oil in Tokyo Bay     

Jiro Koyama  Chie Imakado  Seiichi Uno  Takako Kuroda  Shouichi Hara  Takahiro Majima  Hideyuki Shirota  Nathaniel C. Añasco 《Marine pollution bulletin》2014

To assess risks of chemically-dispersed oil to marine organisms, oil concentrations in the water were simulated using a hypothetical spill accident in Tokyo Bay. Simulated oil concentrations were then compared with the short-term no-observed effect concentration (NOEC), 0.01 mg/L, obtained through toxicity tests using marine diatoms, amphipod and fish. Area of oil concentrations higher than the NOEC were compared with respect to use and non-use of dispersant. Results of the simulation show relatively faster dispersion near the mouth of the bay compared to its inner sections which is basically related to its stronger water currents. Interestingly, in the inner bay, a large area of chemically-dispersed oil has concentrations higher than the NOEC. It seems emulsifying oil by dispersant increases oil concentrations, which could lead to higher toxicity to aquatic organisms. When stronger winds occur, however, the difference in toxic areas between use and non-use of dispersant is quite small.  相似文献   

Influence of fine sediment on the fluidity of debris flows     

Norifumi Hotta  Takahiro Kaneko  Tomoyuki Iwata  Haruo Nishimoto 《山地科学学报》2013,10(2):233-238

Debris flows include a great diversity of grain sizes with inherent features such as inverse grading, particle size segregation, and liquefaction of fine sediment. The liquefaction of fine sediment affects the fluidity of debris flows, although the behavior and influence of fine sediment in debris flows have not been examined sufficiently. This study used flume tests to detect the effect of fine sediment on the fluidity of laboratory debris flows consisting of particles with various diameters. From the experiments, the greatest sediment concentration and flow depth were observed in the debris flows mixed with fine sediment indicating increased flow resistance. The experimental friction coefficient was then compared with the theoretical friction coefficient derived by substituting the experimental values into the constitutive equations for debris flow. The theoretical friction coefficient was obtained from two models with different fine-sediment treatments: assuming that all of the fine sediments were solid particles or that the particles consisted of a fluid phase involving pore water liquefaction. From the comparison of the friction coefficients, a fully liquefaction state was detected for the fine particle mixture. When the mixing ratio and particle size of the fine sediment were different, some other cases were considered to be in a partially liquefied transition state. These results imply that the liquefaction of fine sediment in debris flows was induced not only by the geometric conditions such as particle sizes, but also by the flow conditions.  相似文献   

Holocene paleolimnological changes in Lake Skallen Oike in the Syowa Station area of Antarctica inferred from organic components in a sediment core (Sk4C-02)     

Genki I. Matsumoto  Yukinori Tani  Koji Seto  Tomoko Tazawa  Masumi Yamamuro  Takahiro Watanabe  Toshio Nakamura  Tetsuo Takemura  Satoshi Imura  Hiroshi Kanda 《Journal of Paleolimnology》2010,44(2):677-693

Antarctic climate changes influence environmental changes at both regional and local scales. Here we report Holocene paleolimnological changes in lake sediment core Sk4C-02 (length 378.0 cm) from Lake Skallen Oike in the Soya Kaigan region of East Antarctica inferred from analyses of sedimentary facies, a range of organic components, isotope ratios of organic carbon and nitrogen, and carbon-14 dating by Tandetron accelerator mass spectrometry. The sediment core was composed of clayish mud (378.0–152.5 cm) overlain by organic sediments (152.5 cm-surface). The age of the surface and the core bottom were 150 (AD1950-1640) and ca. 7,030 ± 73 calibrated years before present (cal BP), respectively, and the mean sedimentation rate was estimated to be 0.55 mm/year. Multi-proxy analyses revealed that the principal environmental change in the core is a transition from marine to lacustrine environments which occurred at a depth of 152.5 cm (ca. 3,590 cal BP). This was caused by relative sea level change brought about by ongoing retreat of glaciers during the mid-Holocene warming of Antarctica, and ongoing isostatic uplift which outpaced changes in global (eustatic) sea level. The mean isostatic uplift rate was calculated to be 2.8 mm/year. The coastal marine period (378.0–152.5 cm, ca. 7,030–3,590 cal BP) was characterized by low biological production with the predominance of diatoms. During the transition period from marine to freshwater conditions (152.5-approximately 135 cm, ca. 3,590–3,290 cal BP) the lake was stratified with marine water overlain by freshwater, with a chemocline and an anoxic (sulfidic) layer in the bottom of the photic zone. Green sulfur bacteria and Cryptophyta were the major photosynthetic organisms. The Cryptophyta appeared to be tolerant of the moderate salinity and stratified water conditions. The lacustrine period (approximately 135 cm-surface, ca. 3,290 cal BP-present) was characterized by high biological production by green algae (e.g. Comarium clepsydra and Oedegonium spp.) with some contributions from cyanobacteria and diatoms. Biological production during this period was 8.7 times higher than during the coastal marine period.  相似文献